Area of expertise?
Dunno man, we are talking about a legendary blatant bug that is there for years, which makes me think that maybe the devs that are there they just can’t do it, because it’s not their thing, you know, not their area of expertise.
Hope I’m wrong. 
Multiresolution in Blender was developed in Blender in 2006 and at the time, was quite experimental (even in zbrush). Sergey touched the code in 2011 to add support for deformations and animations for Sintel i believe. I think problems arise later when bmesh was added but i can’t remember details. Since Nick Bishop departed around that time there was some problems with sculpt mode and spikes that were solved by Brecht and/or Jason Wilkins in a gsoc around the same time (wasn’t resolved there, but work began at the time, took some years to get rid of it completely), but the multiresolution problem was noticed later.
Since then, only Sergey Sharibin knows the behemoth of code that manages multiresolution (I believe at the time, he called it “crazyspace” or something like that), so he’s the man that “maybe” can fix it, without resorting to a full rewrite.
Let’s hope for the better.
My impression is that prior to Pablo Dobarro, sculpting has been a very low priority feature of Blender, with what little development happening being the result of GSOC student projects.
Now there is a fulltime developer who can focus exclusively on Blender sculpting and he has declared that fully working multires is a key aspect of the new Blender sculpting workflow he is creating. I believe your pessimism is getting the better of you. Cheer up!
In the Sculpt Quest Proposal he talks about a new sculpt data structure optimized for tessellation and multiresolution, idk if that will fix all the problems he also said that it was a long term thing so maybe in 2.84-85?
Multires should be torn out and rewritten. The code that handles it is some of the ugliest I’ve ever seen, and that’s saying something. There are modern designs and white papers for how to properly handle the types of data that the modifier will have to handle that have been written and updated since the original modifier was created. It will be a large task, but not as nightmarish as some might imagine.
Agree, multires for 2.8 is somehow worst than it was in 2.79. I’d rather not have any multires modifier if that means the devs can concentrate in doing a new and improved version of it, even if it means we have to wait until 2.85 or 2.86.
Personally, for any task involving multires I’ll keep using 2.79, sculpt, detail, bake maps and then back to 2.81.
Yes. What Regnas showed is clearly the problem.
Adding a subdivision level forces user to smooth a huge part of sculpt and maybe re-sculpt what was already done before detailing.
Apply base button is probably solvable. Only highest level is editable, now.
Button could be greyed out if preview level is not zero.
Apply base destroys the sculpt too, in the latest version it seems it’s deforming the mesh twice, at the base level and then again on whatever subdivision level is active.
That is too old, this proposal was written before he officially joins Blender and at that time he didn’t discuss with Brecht or Sergey, so the proposal is too old.
I have crying for this for long long time " multires. overhaul " This is the perfect time i have never seen so many people knowing multires. code working in Blender at the same time: Campbell, Sergey, Brecht, Pablo, … and there is even a in-house sculptor. This is our good chance to have multires. problem solved if we miss it we will cry for eternity 
Yes. It does. But If preview level is set to zero, it just deforms mesh at base level.
So, if there is a technical problem that prevents the button to work correctly at subdivision level, you just have to forbid access to Apply Base button unless Preview level is zero.
Problem is solved and feature is preserved.
I know this is more wishful thinking than a realistic expectation, but it would be amazing if the fixes (or rewrite) to the multires modifier allow us to finally use shapekeys with multires, or any other implementation of layers for sculpting…
Don’t hold your breath.
It’s green.
Just download latest 2.82 alpha and still these clay brushes are not yet in there!
Yeah… green since they put it on the to-do list, but it’s something we’ve been asking since 2.5 
Now that I think about it, in an older version (can’t remember which) it was possible to use shapekeys with multires. I used it once for something at work, had to add extra detail/deformation to a pillow animation, and multires+animated shapekey was the quickest solution without simulating the whole thing again.
I guess it was considered a bug or something because I haven’t been able to replicate that workflow since then.
The review process is happening very very slow lately. Maybe next year. 
The review process is slow right now because the devs. are spending a lot of time working the bug tracker and fixing bugs (for the 2.81 release). The dev. notes even say that a lot of time in this area is expected.
Then you combine that with Brecht having time off as a reward for his exhaustive work on 2.80.
My point exactly.
Yep at this rate it is surely going to be next year! 